AMPA-type glutamate receptors (AMPARs) mediate the majority of fast, excitatory neurotransmission in the central nervous system, and the number and subunit composition of AMPARs are major determinants of synaptic strength. AMPARs are heterotetramers made up of the subunits GluR1-4. GluR2 is particularly important for determining the properties of the receptor: receptors that lack GluR2 pass Ca2+ and have different kinetics and single-channel conductances than those with GluR2. Thus, the relative amount of GluR2 at the post-synaptic density (PSD) has a major effect on synaptic efficacy. Indeed, the ratio of GluR2-containing to GluR2-lacking AMPARs at the PSD may be regulated in both mGluR- and NMDAR-dependent forms of plasticity.
In non-neuronal cells, extracellular signals regulate endosomal trafficking through protein kinase D1 (PKD1). PKD1 facilitates the recycling of β3 integrins to focal adhesions in epithelia during wound-healing and mediates Ca2+-dependent insulin secretion in pancreatic β cells.